/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using Spring.Expressions;
using Spring.Util;

namespace Spring.Validation.Validators;

/// <summary>
/// Perform credit card validations.
/// </summary>
/// <remarks>
/// By default, all supported card types are allowed. You can specify
/// which credit card type validator should be used by setting
/// the value of <see cref="CardType"/> property to a concrete <see cref="ICreditCardType"/>
/// instance.
/// </remarks>
public class CreditCardValidator : BaseSimpleValidator
{
    /// <summary>
    /// Credit card type validator to use.
    /// </summary>
    /// <remarks>
    /// Can be concrete implementations of <see cref="ICreditCardType"/>
    /// interface. The following are available implementations:
    /// <see cref="Visa"/>, <see cref="Mastercard"/>, <see cref="Amex"/>,
    /// <see cref="Discover"/>.
    /// </remarks>
    public ICreditCardType CardType
    {
        get { return m_cardType; }
        set { m_cardType = value; }
    }

    /// <summary>
    /// Creates a new instance of the <b>UrlValidator</b> class.
    /// </summary>
    public CreditCardValidator()
    {
    }

    /// <summary>
    /// Creates a new instance of the <b>UrlValidator</b> class.
    /// </summary>
    /// <param name="test">The expression to validate.</param>
    /// <param name="when">The expression that determines if this validator should be evaluated.</param>
    /// <param name="cardType">Credit Card type validator to use.</param>
    public CreditCardValidator(string test, string when, ICreditCardType cardType)
        : base(test, when)
    {
        AssertUtils.ArgumentHasText(test, "test");
        this.m_cardType = cardType;
    }

    /// <summary>
    /// Creates a new instance of the <b>UrlValidator</b> class.
    /// </summary>
    /// <param name="test">The expression to validate.</param>
    /// <param name="when">The expression that determines if this validator should be evaluated.</param>
    /// <param name="cardType">Credit Card type validator to use.</param>
    public CreditCardValidator(IExpression test, IExpression when, ICreditCardType cardType)
        : base(test, when)
    {
        AssertUtils.ArgumentNotNull(test, "test");
        this.m_cardType = cardType;
    }

    /// <summary>
    /// Validates the supplied <paramref name="objectToValidate"/>.
    /// </summary>
    /// <remarks>
    /// In the case of the <see cref="CreditCardValidator"/> class,
    /// the test should be a string variable that will be evaluated and the object
    /// obtained as a result of this evaluation will be checked if it is
    /// a valid credit card number.
    /// </remarks>
    /// <param name="objectToValidate">The object to validate.</param>
    /// <returns>
    /// <see lang="true"/> if the supplied <paramref name="objectToValidate"/> is valid
    /// credit card number.
    /// </returns>
    protected override bool Validate(object objectToValidate)
    {
        string text = objectToValidate as string;
        if (StringUtils.IsNullOrEmpty(text))
        {
            return true;
        }

        return IsValid(text);
    }

    /// <summary>
    /// Checks if the <paramref name="card"/> is a valid credit card number.
    /// </summary>
    /// <param name="card">
    /// The card number to validate.
    /// </param>
    /// <returns>
    /// <b>true</b> if the card number is valid.
    /// </returns>
    public bool IsValid(String card)
    {
        // check card number length
        if ((card == null) || (card.Length < 13) || (card.Length > 19))
        {
            return false;
        }

        // check if the card is a valid credit card number
        if (!LuhnCheck(card))
        {
            return false;
        }

        // validate card with credit card type validator
        if (CardType != null)
        {
            return ValidateCard(card);
        }
        else
        {
            throw new ArgumentException("Property CardType cannot be null.");
        }
    }

    /// <summary>
    /// Validates card number with the specified <see cref="CardType"/> validator.
    /// </summary>
    /// <param name="cardNumber">
    /// Credit card number to validate.
    /// </param>
    /// <returns>
    /// <b>true</b> if credit card number is a valid number of credit card type specified.
    /// </returns>
    private bool ValidateCard(string cardNumber)
    {
        String card = cardNumber == null ? null : cardNumber.Trim();

        if (card == null)
        {
            return false;
        }

        return CardType.Matches(card);
    }

    /// <summary>
    /// Checks for a valid credit card number.
    /// </summary>
    /// <param name="cardNumber">
    /// Credit Card Number.
    /// </param>
    /// <returns>
    /// <b>true</b> if the card number passes the LuhnCheck.
    /// </returns>
    private bool LuhnCheck(string cardNumber)
    {
        // number must be validated as 0..9 numeric first!!
        int digits = cardNumber.Length;
        int oddOrEven = digits & 1;
        long sum = 0;
        for (int count = 0; count < digits; count++)
        {
            int digit;
            try
            {
                digit = Int32.Parse(cardNumber[count] + "");
            }
            catch (FormatException)
            {
                return false;
            }

            if (((count & 1) ^ oddOrEven) == 0)
            {
                // not
                digit *= 2;
                if (digit > 9)
                {
                    digit -= 9;
                }
            }

            sum += digit;
        }

        return (sum == 0) ? false : (sum % 10 == 0);
    }

    private ICreditCardType m_cardType;
}

/// <summary>
/// CreditCardType interface defines how validation is performed
/// for one type/brand of credit card.
/// </summary>
public interface ICreditCardType
{
    /// <summary>
    /// Returns true if the card number matches this type of
    /// credit card.
    /// </summary>
    /// <param name="card">
    /// The card number, never null.
    /// </param>
    /// <returns>
    /// <b>true</b> if the number matches.
    /// </returns>
    bool Matches(String card);
}

/// <summary>
/// Visa credit card type validation support.
/// </summary>
public class Visa : ICreditCardType
{
    private static readonly String PREFIX = "4";

    /// <summary>
    /// Indicates, wheter the given credit card number matches a visa number.
    /// </summary>
    public bool Matches(String card)
    {
        return (card.Substring(0, 1).Equals(PREFIX) && (card.Length == 13 || card.Length == 16));
    }
}

/// <summary>
/// American Express credit card type validation support.
/// </summary>
public class Amex : ICreditCardType
{
    private static readonly String PREFIX = "34,37,";

    /// <summary>
    /// Indicates, wheter the given credit card number matches an amex number.
    /// </summary>
    public bool Matches(String card)
    {
        String prefix2 = card.Substring(0, 2) + ",";
        return ((PREFIX.IndexOf(prefix2) != -1) && (card.Length == 15));
    }
}

/// <summary>
/// Discover credit card type validation support.
/// </summary>
public class Discover : ICreditCardType
{
    private static readonly String PREFIX = "6011";

    /// <summary>
    /// Indicates, wheter the given credit card number matches a discover number.
    /// </summary>
    public bool Matches(String card)
    {
        return (card.Substring(0, 4).Equals(PREFIX) && (card.Length == 16));
    }
}

/// <summary>
/// Mastercard credit card type validation support.
/// </summary>
public class Mastercard : ICreditCardType
{
    private static readonly String PREFIX = "51,52,53,54,55,";

    /// <summary>
    /// Indicates, wheter the given credit card number matches a mastercard number.
    /// </summary>
    public bool Matches(String card)
    {
        String prefix2 = card.Substring(0, 2) + ",";
        return ((PREFIX.IndexOf(prefix2) != -1) && (card.Length == 16));
    }
}